Using growth models to relate acquisition of nicotine self-administration to break point and nicotinic receptor binding

Eric C. Donny, Stephanie T. Lanza, Robert L. Balster, Linda M. Collins, Anthony Caggiula, Peter P. Rowell

Research output: Contribution to journalArticlepeer-review


Growth modeling can be used to characterize individual and mean acquisition trajectories for drug self-administration. Individual characteristics can also be incorporated into the growth model, providing a powerful tool for investigating the relationship between acquisition and other behavioral and biological measures. We illustrate the utility of this method by examining the relationship between acquisition of nicotine self-administration and (1) break point on a progressive ratio schedule of reinforcement, and (2) the density of brain nicotinic receptors (Bmax). Daily infusion rates from male and female Sprague-Dawley rats were modeled with break point or Bmax as time-invariant covariates. Use of this model led to two novel findings regarding individual differences in acquisition. First, greater rates of change in infusions early in acquisition were related to higher break points; this relationship was mediated by a similar effect of increasing the number of responses required to obtain nicotine. Second, animals displaying more resistance to increases in the response requirement during acquisition, as indicated by a smaller drop in the rate of nicotine self-administration, generally had fewer nicotinic receptors at the end of the experiment. The relationships revealed demonstrate the usefulness of growth models in the quantitative analysis of individual differences in drug self-administration behavior.

Original languageEnglish (US)
Pages (from-to)23-35
Number of pages13
JournalDrug and alcohol dependence
Issue number1
StatePublished - Jul 15 2004


  • Growth curve modeling
  • Hierarchical linear modeling
  • Individual differences
  • Learning
  • Self-administration
  • Trajectory

ASJC Scopus subject areas

  • Toxicology
  • Pharmacology
  • Psychiatry and Mental health
  • Pharmacology (medical)


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